This is a revised proposal for the establishment of an independent center at Dartmouth for the development and application of EPR techniques for studies in functional biological systems, especially in vivo EPR spectroscopy. It builds upon the experience and progress made in the laboratory of the PI, including activities at Dartmouth since 1/1/92 as a subcontract of the IERC. The proposed activities of the Center will cover the full spectrum of a Research Resource: I. CORE RESEARCH- The theme is to extend and improve the capabilities of carrying out EPR studies in vivo, including developments aimed specifically at extending capabilities to larger animals an determining the feasibility of effective clinical applications. The principal development projects will include: A. To improve the current L-Band instruments; B. To develop and improve resonators for use in vivo; C. To develop a "transportable" L-Band EPR that can be used at various sites, including in clinical settings; D. In collaboration with the National Biomedical ESR Center to develop a new lower frequency (600 MHz) instrument based on the multi-quantum approach. II. COLLABORATIVE RESEARCH- This is aimed at providing access to the instrumentation for local, regional, national and international users whose experimental needs require the equipment and/or expertise available at the Center, especially in regard to studies of viable biological systems. The collaborative research projects cover three principle themes: A. Using EPR to Measure po in Viable Biological Systems; B. The Detection and Characterization of Reactive Species from Living Animals; C. Using EPR to Measure Pharmacological Parameters in Viable Biological Systems. III. SERVICE- The theme of the service component is to act as a source of advice and pilot experiments for scientists potentially needing the type of facilities at the Center and to act as a world-wide referral site for information on EPR in functional biological systems. IV. EDUCATION- To provide educational opportunities in the field for young investigators, established investigators entering this field, and established investigators in this field through short term visits, long term visits, and periodic workshops. V. DISSEMINATION- To make available to the user community all of the instrumental and conceptual developments of the Center through descriptions, schematics, and on site examination of our developments.